# scipy.signal.kaiser_atten¶

scipy.signal.kaiser_atten(numtaps, width)[source]

Compute the attenuation of a Kaiser FIR filter.

Given the number of taps N and the transition width width, compute the attenuation a in dB, given by Kaiser’s formula:

a = 2.285 * (N - 1) * pi * width + 7.95

Parameters
numtapsint

The number of taps in the FIR filter.

widthfloat

The desired width of the transition region between passband and stopband (or, in general, at any discontinuity) for the filter, expressed as a fraction of the Nyquist frequency.

Returns
afloat

The attenuation of the ripple, in dB.

Examples

Suppose we want to design a FIR filter using the Kaiser window method that will have 211 taps and a transition width of 9 Hz for a signal that is sampled at 480 Hz. Expressed as a fraction of the Nyquist frequency, the width is 9/(0.5*480) = 0.0375. The approximate attenuation (in dB) is computed as follows:

>>> from scipy.signal import kaiser_atten
>>> kaiser_atten(211, 0.0375)
64.48099630593983


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